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Case studies

How Perranwell proactively mitigated flood impacts during Storm Henk

Perranwell is a Cornish village that uses Previsico's Flood Warning Service to alert the local community during period of flood.


Perranwell is a Cornish village located about halfway between Truro and Falmouth. The Parish is made up of approximately 750 properties that have suffered from flooding over the years, mainly due to the river running through the centre of the parish. 


At the end of 2023 and the start of 2024, the UK experienced heavy rainfall and frequent storm events such as Storm Babet, Ciaran and Henk. These weather events meant that Cornwall and more specifically Perranwell experienced a significant amount of rainfall.  


The community were keen to take preventative measures and setup an emergency plan working group (EPWG) to undertake a risk survey, prioritising property flood resilience (PFR).

Louisa Inch of Premier Water Solutions also provided specialist advice on their emergency plan. 

To effectively manage this risk, Previsico, in partnership with Watertight International, work with the EPWG, installing a flood sensor in Perranwell Station over the bridge to protect the local community from fluvial flooding. The device replaces a legacy instrument that had stopped working and monitors water depth within Trewedna Water – an ordinary watercourse that runs through the village. The device is configured to generate alerts for the local community during periods of flood.  

During Storm Henk, the sensor provided Louisa Inch and others in the community with two alerts across the 2nd - 5th January 2024 that the water level had gone over the first threshold (yellow horizontal line).

These alerts were provided late at night and into the early morning when people wouldn’t be actively checking the changing water levels. After receiving the alerts, Councillor Richard Holman was then able to visit the site and conduct a visual check to decide whether emergency measures need to be put in place.

Impact on the community

Fortunately, the water levels on both occasions didn’t increase much further and the rain stopped so no emergency measures needed to take place and no flooding occurred.

However, having the real-time data from the sensor did assist the community and parish council to make well informed decisions in order to prevent significant impacts from flooding.  

Many people in the Parish benefit from the installed device, with this only realised through the sound actions of the EPWG and Emergency Plan. Nearby to the river there is a classic car garage that with early warnings are able to move their vehicles and equipment to a safer space, saving the business money from potential damages. There are also 11 residential homes that are extremely close to the watercourse and at significant risk of flooding, some with elderly residents who can prepare by moving furniture and valuable items up from the ground floor.  

The incident underscores the effectiveness of EPWG team in actioning timely and actionable information from Previsico to prevent loss. By leveraging this advanced technology, Perranwell was able to contribute to the overall resilience of the community, preventing potential disruptions to essential services and costly damages to businesses and homes.

Following the valuable alerts issued by Previsico during storm Henk, it is evident that the installation of the device has been beneficial to many people in our Parish, highlighting the importance of collaboration between local authorities, community groups, and Previsico in addressing environmental challenges like flooding.
Councillor Richard HolmanPerran ar Worthal Emergency Plan Co-ordinator and Chair of the Emergency Plan Working Group